The 16th New Hampshire Infantry was organized in Concord, New Hampshire, and mustered into Federal service on October 24, 1862, for nine months' service under the command of Colonel James Pike.

The regiment left New Hampshire for New York November and joined Banks' Expeditionary Corps.

Attached to Sherman's Division, Department of the Gulf, to January 1863.

Operations on Bayou Plaquemine and the Black and Atchafalaya rivers February 12–28.

Ordered to Port Hudson May 30, and assigned as guard at arsenal of Banks' Army at Springfield Landing June 3 to July 9.